When Jesus consented to the crucifixion, which was followed by the resurrection, he was demonstrating that death is not necessary to the achievement of immortality. His earthly career exemplified this, and the human need that it be brought more sharply into focus was met by his selfless obedience to divine direction.
His disciples and other devoted followers glimpsed this truth to a great extent, for Paul wrote to Timothy that God's purpose "is now made manifest by the appearing of our Saviour Jesus Christ, who hath abolished death, and hath brought life and immortality to light through the gospel." II Tim. 1:10; Although Jesus' followers may have acknowledged that death has no power to end the life of anyone, they had not reached the understanding of this truth nor demonstrated it on the basis that our Master did by his own reappearance in fleshly form.
The tenacity of error seems to hold men in bondage to the belief in death, a lie of limitation regarding life and goodness. However, every earnest prayer and proof of God's power and ever-presence is lessening this hold on human consciousness, just as the continued efforts to prove that men could make machines that could fly have brought us to the jet age, wherein all may enjoy the benefits of this advance in methods of transportation.